Gilbert Newton Lewis

Born Oct. 23, 1875, in Wey-mouth, Mass., near Boston; died Mar. 23, 1946, in Berkeley, Calif. American physical chemist; member of the US National Academy of Sciences in Washington, D.C.

Lewis graduated from Harvard University in 1896 and became a professor at the University of California at Berkeley in 1912. Most of his research dealt with chemical thermodynamics and a theory of the structure of matter. Lewis proposed a new formulation of the third principle of thermodynamics, contributing to a more precise definition of absolute entropy. He developed methods of calculating the free energy of chemical reactions and introduced the concepts of thermodynamic activity (1907) and volatility. He proposed the electron theory of chemical bonding (1912-16) and was the first to produce heavy water D₂O (1933, jointly with R. MacDonald) and to isolate deuterium, the heavy isotope of hydrogen. A number of his studies were devoted to the theory of acids and bases, the formation of complexes, solubility, and the chromaticity of organic compounds. Lewis inspired a number of followers among his fellow chemists. He was made an honorary member of the Academy of Sciences of the USSR in 1942.